1. Field of the Invention
This invention relates to a seat belt anchorage system for a conversion van. More particularly, this invention relates to a seat belt anchorage system itself, to a conversion van which includes a seat belt anchorage system, and to a method of installing a seat belt anchorage system in a conversion van.
2. Background of the Related Art
A van conversion vehicle is first manufactured as an incomplete vehicle by an automotive chassis manufacturer. The term incomplete vehicle refers to a vehicle which is mechanically a full functioning vehicle, but it has no interior components. The incomplete vehicle has no seat belt anchorages except for the two front seat belts and shoulder harnesses. Incomplete vehicles are manufactured by General Motors, Ford Motor Company and Chrysler Corporation.
The second stage manufacturer, or conversion company, installs the interior components to complete the vehicle, including an audio system, wheels, trim, upholstery, seating, wood finishes and electrical components. It is the responsibility of the conversion company to install the interior and modify the vehicle, particularly with respect to seat belts, in accordance with Federal Motor Vehicle Safety Standards (FMVSS).
FMVSS Standard No. 207, which relates to seating systems for passenger vehicles, including vans, establishes minimum safety requirements for seats, their attachment assemblies, and their installation, to minimize the possibility of failure as a result of forces acting on the seat in the event of vehicle impact. FMVSS Standard No. 210, which relates to seat belt anchorages for passenger vehicles, including vans, specifies the minimum safety requirements for seat belt assembly anchorages to ensure effective occupant restraint and to reduce the likelihood of failure in a collision.
FMVSS Standard No. 207 requires that each occupant seat withstand certain forces when tested in accordance with established test procedures. These forces include 20 times the weight of the seat applied in a forward longitudinal direction and a force that produces a 3,300 inch-pound moment about the seating reference point. In addition, if a seat belt assembly is attached to the seat, the seat must withstand a force of 20 times the weight of the seat applied simultaneously with a force imposed on the seat by the seat belt assembly when loaded in accordance with FMVSS Standard No. 210.
The weight of the seat assembly in most cars consists almost entirely of the seat pan, the seat back, and the seat adjuster. The fixed portion of the seat assembly that is fastened to the floor of the car contributes only a minor portion to the overall weight of the seat assembly. Special difficulties have arisen, though, when the FMVSS 207 testing procedures have been applied to pedestal seats of the kind used in many trucks and recreational vehicles, including those used in conversion vans.
A pedestal seat consists of a seat mounted on a seat adjuster, which in turn is attached to the top of a pedestal. In this application, the seat belt assembly is typically attached to the pedestal. The difficulties with testing a pedestal seat arise from its unusual weight distribution. In some cases, close to half of the weight of the assembly is in the pedestal. A similar weight distribution problem occurs with sofa-type or bench-type seats often located at the rear of a van. Because the unusual weight distribution, manufacturers were testing the seats separately from the pedestal.
A conversion van typically has a pair of mid-position captains-type chairs (one on the driver's side and one on the passenger side), and a sofa seat at the rear of the vehicle. The seat belt assembly on a captain's chair has been typically attached to the seat pedestal, and the pedestal has been merely bolted to the floor. The seat belt assemblies for the rear sofa seat have typically been attached to a seat belt bar which extends across the floor of the vehicle behind the sofa seat. The sofa seat belt bar has ordinarily been bolted to the floor of the van.
NHTSA recently tested the seat belt assembly anchorages on conversion vans from three conversion companies. All three vans tested failed. Two of the vans tested utilized seat belt bars to anchor the seat belts on the rear sofa seat. In each instance the seat belt bar was substantially deformed and pulled completely out of the floor when the test force was applied. A mid-position captain's chair in one van failed when the pedestal broke in two, causing the test to be aborted before the full load could be applied. In testing other pedestal seats in the vans, it was noted that, while the seats did not break loose, nevertheless they bent all the way forward so as to possibly endanger the occupants when coming in contact with rigid parts of the vehicle.
The tests conducted by NHTSA revealed several shortcomings in the current practice of anchoring seat belts in conversion vans. Testing of the seating components such as the seats, pedestals and seat belts has previously been conducted on an individual component basis and the tests have been run on a non-yielding testing apparatus. The test results under such laboratory conditions may bear no relation to those which would be found in actual vehicle applications. Moreover, van converters typically used the test data from the individual component manufacturers to determine whether a combination of components complied with the federal standards. That is, a seat, a pedestal, and a seat belt which may have been individually certified as being in compliance with federal standards, have been assumed by the van converter to also be in compliance when installed as a combination in a van conversion vehicle. The total seating system has previously not been tested for compliance.
Furthermore, the seat belt angle changes with the interchange of seating components. The intent of FMVSS Standard No. 210 is to have the lap belt distribute the crash load to the pelvis of the occupant. FMVSS Standard No. 210 currently requires the seat belt angle to be not less than 20.degree. nor more than 75.degree., and a change in the standard effective in 1992 will require the seat belt angle to be not less than 30.degree. nor more than 75.degree.. NHTSA found in some conversion vans, however, that the seat combination actually had an effective angle of up to 90.degree.. When the seat belt angle exceeds 75.degree., the belt will load the legs rather than the pelvis, causing more serious injury. Furthermore, a seat belt with an effective angle near 90.degree. will not properly restrain a child safety seat.
Finally, an occupant of a pedestal seat may be endangered during a crash because the occupant and the seat may rotate forward and come in contact with rigid parts of the vehicle.
In response to the shortcomings disclosed by its testing, NHTSA recently amended FMVSS Standard No. 207 by prescribing new test procedures for pedestal seats that NHTSA believes more closely represent the load distribution actually experienced by pedestal seats in real world crashes. FMVSS Standard No. 207 now requires a single test for pedestal seats which simultaneously applies two loads. A first load of 20 times the weight of the upper seat is applied horizontally through the center of gravity of that portion of the seat. Simultaneously, a second load of 20 times the weight of the pedestal is applied horizontally through the pedestal's center of gravity. If the seat belt is mounted on the seating system, the load required under FMVSS Standard No. 210 is applied at the same time.